Scientific name: Polyvinyl alcohol

English name: Polyvinyl alcohol

English abbreviation: PVA

Polyvinyl alcohol (PVA) is produced through the polymerization of vinyl acetate followed by alcoholysis. It is a white, stable, non‑toxic, water‑soluble polymer, existing as a powdery, flaky, or flocculent solid.

Polyvinyl alcohol contains numerous alcohol groups, which are polar and capable of forming hydrogen bonds with water, allowing it to dissolve in polar water. It is also soluble in hot hydroxyl‑containing solvents such as glycerol and phenol, but is insoluble in common organic solvents like methanol, benzene, acetone, and gasoline.

1. Physicochemical Properties

I. Physical Properties

A. Solubility: Polyvinyl alcohol powder is soluble in water. Polyvinyl alcohol resins (PVA) with a degree of hydrolysis less than 95% can dissolve in room‑temperature water, while polyvinyl alcohol resins (PVA) with a degree of hydrolysis greater than 99.5% can only dissolve in hot water above 95°C.

B. Thermal Stability: Polyvinyl alcohol softens when heated; it shows no significant changes below 40°C. Its glass transition temperature is 75–85°C. When heated above 100°C, it gradually discolors and becomes brittle. At temperatures above 160°C, prolonged heating leads to gradual coloration, dehydration etherification, and loss of solubility. Above 220°C, it undergoes decomposition, yielding water, acetic acid, acetaldehyde, and butenal; when the temperature exceeds 250°C, it transforms into a polymer containing conjugated double bonds.

C. Chemical Resistance: PVA is virtually unaffected by weak acids, weak bases, or organic solvents and exhibits excellent oil resistance.

D. Storage Stability: PVA is a low‑viscosity polymer, and its aqueous solution is highly stable at room temperature. The aqueous solution does not deteriorate during storage.

E. Film‑Forming Properties: Due to the high adhesion between PVA molecules, PVA readily forms a film that is colorless and transparent, exhibiting excellent mechanical strength, a smooth and non‑sticky surface, and superior solvent resistance. The molecular film boasts good light transmittance, a high moisture permeability, is non‑charged, does not attract dust, and offers excellent printability.

II. Chemical Properties

PVA can be regarded as a linear polymeric material containing secondary hydroxyl groups. The hydroxyl groups in its molecular structure are highly reactive and capable of undergoing typical chemical reactions characteristic of lower alcohols, such as esterification, etherification, and acetalization; they can also react with numerous inorganic or organic compounds.

2. Packaging, Transportation, and Storage:

Product Appearance: White, flocculent, flaky, or powdery solid. This product is non‑hazardous, non‑explosive, non‑oxidizing, non‑corrosive, non‑radioactive, and non‑toxic or harmful.

1. Packaging

12.5 kg, 20 kg, or 25 kg in plastic woven bags or paper bags, or packaged in 750 kg to 1000 kg plastic woven bulk bags.

2. Transportation

Use clean transportation tools to prevent moisture, rain, and sunlight; handle with care during transport to avoid scratching or damaging the packaging.

3. Storage

Store in a dry, well‑ventilated indoor environment at room temperature between 5–30°C. Keep away from heat sources, strictly prevent exposure to moisture, and avoid direct sunlight. Absolutely do not store together with volatile chemicals to prevent adsorption and degradation.

3. Product Applications

Aqueous solutions of polyvinyl alcohol (PVA) exhibit excellent film‑forming and emulsifying properties. They can serve as protective colloids in high‑polymer emulsion and suspension polymerization reactions.

Polyvinyl alcohol can be used in textile sizing agents, vinylon fibers, paper coating agents, construction materials, adhesives, PVA films, PVB raw materials, and the food and pharmaceutical industries. PVA can also serve as a soil conditioner, polymerization suspending agent and emulsifier, quenching agent, and more. Furthermore, as researchers continue to develop and refine the properties of PVA, its applications are constantly expanding.

Applications of Various Polyvinyl Alcohol (PVA) Grades

1. Vinylon raw material:

Polyvinyl alcohol can be dissolved and spun into fibers, which are then subjected to acetalization to produce vinylon fibers. These fibers can be blended with cotton, wool, viscose fiber, and other materials to create vinylon textiles, widely used in clothing, tarpaulins, curtain cords, fishing nets, and ropes. In general, it is best to select PVA17-99—polyvinyl alcohol with an average degree of polymerization of 1750 ± 50—as the spinning raw material.

2. Warp sizing agent:

a. The sizing agent, primarily formulated with polyvinyl alcohol, exhibits excellent adhesion to cotton, linen, polyester, and vinylon viscose fibers. After film formation, it delivers a smooth, sleek, and polished surface that is both strong and highly abrasion‑resistant, enhancing the weavability of the warp yarns and reducing warp breakage caused by intense movements such as friction, bending, and stretching during weaving, thereby lowering the warp breakage rate on the loom. Moreover, the resulting fabric feels crisp and structured, with a smooth, fine texture and a non‑rough surface.

b. Polyvinyl alcohol is a water‑soluble polymer; it is very convenient for slurry preparation, sizing, and desizing. Generally, polyvinyl alcohol with a relatively low average degree of polymerization (such as PVA 15–99, 16–99, or 17–99) is preferred as a sizing agent.

3. Adhesive:

a. Polyvinyl alcohol aqueous solutions exhibit extremely strong adhesion to cellulose‑containing materials such as paper, fabric, and wood. They offer the advantages of being safe and non‑toxic, and can be used for cardboard lamination, corrugated cardboard bonding, and office glue applications. Kraft paper bags used for packaging heavy goods like cement, fertilizers, and grain also employ PVA as a binder.

b. Polyvinyl alcohol–modified urea‑formaldehyde resin and phenolic resin can be used as adhesives for plywood and man‑made boards.

c. Aqueous solutions of polyvinyl alcohol (by adding appropriate fillers and additives) are also widely used to prepare adhesives required for bonding paper products such as printed materials, bookbinding, paper tubes, and cardboard boxes.

d. Under acid catalysis, polyvinyl alcohol can undergo condensation with formaldehyde, butyraldehyde, glyoxal, or other aldehydes to form polyvinyl alcohol acetals (such as PVAF and PVB) that exhibit enhanced water resistance, adhesion, and mechanical strength. These materials are widely used in construction, coatings, adhesives, and laminated safety glass applications. As the degree of polymerization of PVA increases, the viscosity of the resulting acetals also rises.

e. Polyvinyl alcohol is an excellent protective colloid and dispersant for the production of emulsions (white glue) via homopolymerization of vinyl acetate or copolymerization with other monomers, playing a crucial role in white glue manufacturing. Generally, as the degree of polymerization of polyvinyl alcohol increases, the viscosity of the resulting emulsion also rises. Partially hydrolyzed polyvinyl alcohol (17–88) is often used in combination with fully hydrolyzed polyvinyl alcohol (such as 17–99, 19–99, etc.). Using partially hydrolyzed polyvinyl alcohol can enhance emulsion stability, while employing fully hydrolyzed polyvinyl alcohol can improve the emulsion’s water resistance.

4. Papermaking and Processing:

a. In the papermaking industry, polyvinyl alcohol can be used as a surface sizing agent for paper. It boasts excellent film-forming properties and high film strength, which can enhance the paper’s printability, smoothness, abrasion resistance, fold resistance, oil resistance, and chemical resistance. It is advisable to select PVA with an average degree of polymerization of 1750 ± 50 as a surface sizing agent for paper.

b. Pigment processing agents: These can enhance the whiteness and gloss of coated paper, resulting in excellent print gloss and vibrant colors while improving the paper’s texture. It is best to select polyvinyl alcohol with a relatively high average degree of polymerization.

c. As an internal sizing agent for paper: During papermaking, powdered polyvinyl alcohol is added to the pulp and beaten together with the pulp before sheet formation; this process yields paper with high strength. It is preferable to select polyvinyl alcohol with a relatively high average degree of polymerization.

5. Polyvinyl alcohol film made from this product. It boasts excellent transparency, high tensile and crack‑resistance, good moisture permeability and gas barrier properties, as well as oil and organic chemical resistance. It is also non‑static, making it ideal for packaging textiles.

4. Product Price

The prices of polyvinyl alcohol vary significantly depending on its intended use; the general market price ranges from 10 to 50 yuan/kg, with an average price of 30.5 yuan/kg.